Tired of apologizing for your addiction to a morning mug (or two or three) of coffee? No more need for guilt – that java may be just what the doctor should order.

According to a study in the New England Journal of Medicine, older adults who drink coffee have a lower risk of death overall than non-coffee drinkers. The coffee drinkers were less likely to die from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.

The study was conducted by researchers from the National Cancer Institute (NCI) and AARP. Over 13 years they examined the coffee drinking habits and risk of death in 400,000 U.S. men and women aged 50 to 71. The participants answered a questionnaire as part of the NIH-AARP Diet and Health Study from 1995 to 2008.

More coffee is better

There is even more good news: none of this moderation stuff. The researchers found that the risk of death decreased as the amount of coffee consumed went up. In general, participants who drank three or more cups of coffee per day had a 10% lower risk of death compared to those who drank none.

Men who drank four to five cups of coffee every day reduced their risk of death over the study period by 12%. Women reduced their risk by 16%.

The researchers would not say that coffee causes the lower risk of death. They couldn't explain the association but believe their results "provide some reassurance that coffee drinking does not adversely affect health."

How does coffee lower your risk of death?

According to the researchers the way coffee helps protect against the risk of death is not clear because "coffee contains more than 1,000 compounds that might potentially affect health."

One of those compounds is caffeine but that does not seem to be the key. In the study there were no differences among those who drank decaf or high test.

The researchers also cautioned that they did not have information on how the coffee was prepared (espresso, boiled, filtered, etc.). They speculated that how the coffee is prepared might affect the levels of any protective compounds in the coffee.

Although the study found an association between coffee and lower death rates for a wide range of diseases, this was not true for cancer. However, a Harvard School of Public Health study found that coffee did have a significant and beneficial effect for prostate cancer.

In that study, men who consumed the most coffee (six or more cups daily) had nearly a 20% lower risk of developing any form of prostate cancer and 60% lower risk of developing lethal prostate cancer, a particularly aggressive form of the disease.

The researchers in that study believe that coffee contains many beneficial compounds that act as antioxidants, reduce inflammation, and regulate insulin, all of which may influence prostate cancer.